ALEXANDER SEMENOV / SCIENCE PHOTO LIBRARY ALEXANDER SEMENOV / SCIENCE PHOTO LIBRARY
Sea butterfly (Limacina helicina). Sea butterflies are swimming predatory marine sea snails. They have two wing-like outgrowths (parapodia, lower right) derived from their foot, which they continually flap to swim through the water. They use a mucous web to trap small aquatic organisms such as crustaceans and plankton. Photographed in the White Sea, Russia.
Model release not required. Property release not required.